TY  - BOOK
AU  - Walpole, P.
AU  - Walpole, Paul
TI  - Food production systems: crops and their environment, unit 3
SN  - 0335063713
AV  - S600 .F68 1978
PY  - 1978///
CY  - Milton Keynes
PB  - The Open University Press
ER  -